What is one of the uses for extension seatbelts?

One of the uses for extension seatbelts is to accommodate infants and oversize passengers. Extension seatbelts are designed to provide additional length to standard seatbelts, making it easier for these individuals to secure themselves safely during a flight. For infants, while it's often recommended that they be secured in an appropriate child restraint, an extension can sometimes aid in securing a caregiver alongside them. For oversize passengers, the extension ensures that they can buckle their seatbelt without discomfort and while meeting safety requirements.

In this context, the other options do not align with the primary purpose of extension seatbelts. They are not intended for securing cabin baggage, enhancing comfort, or specifically designed for emergency evacuation scenarios. Thus, the function that directly addresses the needs of infants and oversize individuals is appropriately matched to with the nature of extension seatbelts.